Comparative proteomic analysis of senescence in the freshwater cladoceran Daphnia pulex

Cladocera are small freshwater crustaceans that have attracted considerable attention in recent years. They are commonly used for studying senescence. In this study, we used LC-MS/MS with eight-plex iTRAQ to perform a comparative proteomic analysis of senescence in Daphnia pulex. Of 3076 primordial proteins, 2325 were credible (the remaining were low-confidence proteins) and 247 significantly differentially expressed proteins (DEPs). Of the latter, 87, 91, and 69 DEPs were identified in the Day 15 vs. Day 5, Day 20 vs. Day 5, and Day 25 vs. Day 5 groups, respectively. Gene ontology enrichment analysis showed that oxidative damage may be the main cause of senescence in D. pulex. Using Kyoto Encyclopedia of Genes and Genomes pathway analysis, we found that the peroxisome pathway played an important role in aging. Our results suggest that D. pulex alleviates excessive oxidative damage by altering key enzymes involved in carbohydrate and protein metabolism.